Nature's notebook summer sounds: Cicada adult

By Sandy de Waal Malefyt

Thursday, July 25, 2013

The warmth of the summer sun carrying over into evening provides a range of sounds that rivals spring's choruses. Melodies that are unique to this part of the calendar that we associate with vacations are especially welcoming and relaxing. Refrains from a number of insects, frogs, several familiar birds, and even rustling leaves and lapping waves help bring us to that state of mind where we just enjoy the chorus and cast time aside.

Insects top the list of natural notes replacing the abundance of bird songs in spring. One of my favorites is the chirping of crickets, especially in the evening. The frequency of the chirps generally increases with air temperature.

Different formulas exist to take the number of cricket chirps in a time period and turn them into a measure of the air temperature. One of the simplest, described by the Library of Congress, is to count the number of chirps in 15 seconds, add 37, and you will have roughly the air temperature in degrees Fahrenheit.

The males are usually the ones chirping and vary their vocalizations in tone depending on the reason for making a sound. The sound is produced by the male rubbing a sharp ridge on one wing against a series of wrinkles on another wing.

The chirps might be loud and monotonous to attract a female and then change to quick, softer chirps once the female is near. Telling another male to vacate the area or calling an alarm are two other reasons for chirps.

For over 2,000 years the Chinese have also enjoyed this insect's call by keeping a single male cricket in decorative little cages of material as brass, bamboo, gourd, and even gold, ivory, and jade.

Calling for a mate is a big reason for insect sounds. With the emergence of Brood II of the 17-year cicada in the southeastern part of New York and states south, some have had the experience of hearing how loud a group of insects can be.

When my husband and I were driving south last month on the New York State Thruway just above Poughkeepsie, we became concerned when we heard a loud, high-pitched hum at times coming from, we thought, our newly rotated tires. No check engine indicator lights came on, but we started mentally calculating what another car repair might cost. Finally at a rise in the highway where the road crossed the crest of an oak-bordered hill, my husband noticed a lot of large insects hitting the windshield and flying at the edges of the road. He lowered the windows, and we heard the loud hum that we thought was from our car. It was hundreds of newly emerged adult cicadas flying madly about in search of love and humming a song only another cicada found enticing.

We never thought an outside sound from the side of the road could be so loud that we would think it from our car.

Another familiar summer sound is one we want to avoid - the high-pitched whine of a mosquito nearby searching for a meal. A sound to counter that is the "glunk" and "ju-rum" of frogs that will make that mosquito a meal of its own.

Moving from amphibians to birds that are still calling is the "teacher, teacher, teacher" call of an ovenbird at the lower level of a forest. In the same area, but higher in the trees, might be the all-day singing of the red-eyed vireo. In residential areas there are the melodious house wren and the catbird imitating other birds.

The soft "coo" of a mourning dove joins at times with the morning and evening calls of the American robin.

There are less and less birds to hear as summer goes on because they leave their breeding territories and move to areas with food to forage and fatten up for the fall migration.

Animals are not the only sources of summer sounds. The slight rustling of quaking aspen leaves is one sound even a plant can make with the help of some wind.

Waves hitting the beach on a lake or the ocean have a soothing repetition. Perhaps one of the best sounds for appreciating summer is actually the still, absence of sound on a clear, starlit night when watching for shooting stars or identifying constellations.

Listening for favorite voices as these enriches our time enjoying summer in Nature's Notebook.

Sandy de Waal Malefyt is a local nature enthusiast and science teacher.